The third level, that of "intelligence," _i.e._ the power to compare, calculate, and reflect, and to order one’s life by conscious rule, is exhibited by man. What distinguishes life at this level from mere "sensitive" life is, on the intellectual side, the ability to cognise universal truths, on the conative, the power to live by rule instead of being swayed by momentary "appetition." The former gives us the possibility of science, the latter of moral excellence.[#] [#] _Cf._ Dante’s "Fatti non foste a viver como bruti, Ma per seguir virtute e conosoenza." *Sensation*.--Life manifests itself at the animal level on the cognitive side as sense-perception, on the conative as appetition or desire, on the affective as feeling of pleasure or pain, and in such simple emotional moods as "temper," resentment, longing. Aristotle gives sensation a logical priority over the conative and emotional expression of "animal" life. To experience appetition or anger or desire you must have an object which you crave for or desire or are angry with, and it is only when you have reached the level of presentations through the senses that you can be said to have an object. Appetition or "temper" is as real a fact as perception, but you cannot crave for or feel angry with a thing you do not apprehend. Aristotle’s definition of sense perception is that it is a "capacity for discerning" or distinguishing between "the sensible qualities of things." His conception of the process by which the discernment or distinguishing is effected is not altogether happy. In sense-perception the soul "takes into itself the _form_ of the thing perceived without its _matter_, as sealing-wax receives the shape of an iron seal-ring without the iron." To understand this, we have to remember that for Aristotle the sensible qualities of the external world, colour, tones, tastes, and the rest, are not effects of mechanical stimulation of our sense-organs, but real qualities of bodies. The hardness of iron, the redness of a piece of red wax are all primarily "in" the iron or the wax. They are "forms," or determinations by definite law, of the "matter" of the iron or the wax. This will become clearer if we consider a definite example, the red colour of the wax. In the wax the red colour is a definite combination of the colour-opposites white and black according to a fixed ratio. Now Aristotle’s view of the process of sense-perception is that when I become aware of the red colour the same proportion of white to black which makes the wax red is reproduced in my organ of vision; my eye, while I am seeing the red, "assimilated" to the wax, is itself for the time actually "reddened." But it does not become wax because the red thing I am looking at is a piece of red wax. The eye remains a thing composed of living tissues. This is what is meant by saying that in seeing the colours of things the eye receives "forms"